In a low-backpressure rotary compressor, since an interior space of a shell is configured as a low-pressure suction environment, a gas force applied on a trailing end of a sliding vane is not sufficient to ensure a front end of the sliding vane to closely contact with an outer diameter of a piston, therefore, a zone of the trailing end of the sliding vane needs to be designed as a sliding vane chamber hermetically separated from an inner diameter of the shell, and the sliding vane chamber is provided with a relatively high pressure environment so as to ensure the front end of the sliding vane to closely contact with the outer diameter of the piston. Moreover, as the sliding vane chamber needs to be hermetically separated from the interior space of the shell, a lubrication cannot be realized by using an oil pool in the shell, and thereby it further needs to design a reasonable oil supply path for the sliding vane chamber so as to ensure the lubrication and sealing of the sliding vane.
In addition, in the closed sliding vane chamber, a volume of the sliding vane chamber changes periodically, as the sliding vane moves reciprocatingly. During this change process, when the sliding vane chamber has a minimum volume, a pressure in the sliding vane chamber reaches a maximum value, and when the sliding vane chamber has a maximum volume, the pressure in the sliding vane chamber reaches a minimum value. If a structure volume of the sliding vane chamber is designed unreasonably, when the maximum pressure in the sliding vane chamber is too large, it may appear that the power consumption of the compressor is increased, even that an abnormal large current is resulted in, thus making the electrical motor shut down; when the minimum pressure of the sliding vane chamber is too small, it may also appear that the front end of the sliding vane cannot contact with the outer diameter of the piston closely, such that an impact occurs between the sliding vane and the piston, which generates an abnormal sound and wear and even causing a leakage, thereby deteriorating the performance of the compressor.